Debarking machine having underlying bark-stripping helical rollers and an overlying adjustable pressure roller



2,726,691 Dec- 3. 1955 P. HARWOOD ET AL DEBARKING MACHINE HAVINGUNDERLYING BARK-STRIPPING HELICAL ROLLERS AND AN OVERLYING ADJUSTABLEPRESSURE ROLLER Filed Sept. 7, 1954 5 Sheets-Sheet l Altarney 2 726 691Dec. 13. 1955 P. HARWOOD E! AL DEBARKING MACHINE HAVING UNDERLYINGBARK-STRIPPING HELICAL ROLLERS AND AN OVERLYING ADJUSTABLE PRESSUREROLLER Filed Sept. 7, 1954 3 Sheets-Sheet 2 F/GZ.

Inventor; GOR 0077 a fl gfia s 792L041. BAA-m $544740? Attorney- Unitedtates Patent O 2,726,691 DEBARKING HAVING UNljERLYiNG BARK-STRIPPINGHELICALROLLERS AND AN OVERLYING ADJUSTABLE PRESSURE ROLLER PhilipHarwood, Little Sutton, Wirral, and Gordon Bohert Jacob, Queens Park,Chester, England, assigiors to J. R. Gordon & Co. Limited, Cardiif,Wales, a British company Application September 7', 1954*, Serial N0.454,424

Claims priority, application Great Britain September 9, 1953 8 lairns.(Cl. lid-2&3}

This invention concerns debarking machines and more especially relatesto such machines which are suitable for the treatment of relativelyshort lengths of round timber.

In most known types of debarkingapparatus the log is held whilst one ormoreblades or the like rotate around the log and progressively movealong it, or the blades rotate around it whilst it is moved alongaxially with respect to the center of rotationof the blade or blades.This arrangement is adopted because of the great lengths of timber whichthese machines normally have to accommodate, and consequently they arenormally of large and robust construction, require a considerable amountof adjustment and maintenance, and are usually permanently accommodatedWithin a building, for instance, a saw-mill.

An object of the present invention is to provide a debarking apparatusof relatively small dimensions, and of simple and robust construction,which is capable of being readily transported from place to place, andwhich may be set up and operated in situ where the timber is felled orany other convenient place.

Another object of the present invention is to provide a machine whichwill remove bark and bast in one opera-' tionwithout damage or loss ofwood, and which can handle rough or scrub timber which may contain largenumbers of knots and be irregular in shape. The machine does not haveknives or cutters such as are provided in some earlier constructions,and is therefore very robust and able to stand up to heavy duty andracking conditions. 7

According to the present invention'a debarking machine comprisesrotating stripping means and a pressure-exerting member, said strippingmeans being adapted to convey the timber being stripped through themachineand said pressure-exerting member beingarranged to hold thetimber against the" rotating stripping means and control the feedingspeed.

Preferably the stripping means comprise a pair of short debarkingrollers spaced apart and mounted longitudinally in the direction oftravel of the wood therethrough with their axes parallel. These rollers,which are each driven in the same direction, may carry helicalprojections, for instance in the form of a worm thread or a scroll,which projections effect the stripping of the timber. These helicalprojections are of similar pitch and each preferably has a short taperat the input end. The term taper implies that the external" diameter ofthe projection and the root diameter of the core upon which theprojection is carried are progressively reduced at one end of eachdebarking roller. For example, a section having a taper angle of about30 may be provided'at one end of each debarking roller which then has 'acentral'c'ylindrical length carrying the projection and thereafterterminates in a solid cylindrical end portion of diameter equal to thatof the maximum external diameter of the projection.

The pressure-exerting member may be constituted by a roller, mountedabove the debarkingr'ollers for rota- Tee 2' tion in the same directionas the debarking rollers but at a slower speed about an adjustable axis.

This adjustability enables the pressure roller to beset with thepressure-roller axis at various angles relative to the axes of thedebarking rollers for the purpose of varying the speed of progression oflogs passing through the machine. I v

The invention will now be further described byway of example withreference to the accompanying drawings in which: X I

Fig. 1 is a general side perspective view of a preferred embodiment of adebarking machine according to the invention in the formof a two-wheeledvehicle trailer;

Fig. 2 is a diagrammatic'view from the opposite side of the machinebasically illustrating the invention with certain parts displaced fromthe position they normally occupy or shown toadifierent scale for thesake of clarity;

Fig. 3 is a. fragmentary perspective view of the operating section ofthema'c hine; V V A Pg. 4 is a perspective view similar to Fig. 3 but toan enlarged scale, certain parts being omitted; and

Fig. 5 is a fragmentary perspective detail of part of theoperating'head'. v V r v j I The preferred debarking machine illustratedincludes a main framework generally indicated by it), constituting partof a two-wheeled trailer provided with suitable means. 11 for attachmentto a vehicle. The trailer is provided with adjustable supports or legs12 at each corner in known manner these supports being lowered (asvshown in Fig. I) when the debarking machine is in use and lifted (asshown in Fig. 2 when the machine is being transported. As each supportis adjustable independently, the machine can be made rigid and stableirrespective of the state of the grouncl'on' which it may stand.

Mounted on the framework 10 are two sets of bearings 13a, 13b and Mn,14b, for the rotating. stripping. means constitiittedby rollers 15 and'16. These rollers carry helical projections ISajand 16d, Whichprojections are of similar pitch" but which gradually increase in radiusfrom the infeed end towardtheoutfee'd end, as can be seen from Fig. 4. vThe rollers 15am to are driven in the same direction (anticlockwise asviewed in Fig. 2.) by sprockets 17 and 13 mounted onthe' roller shaftsand chains 19 and 2%, which in turn engage witha double sprocket 21carried by a secondary countershaft 22. Each of the rollers 15 and 16,-and its associated helical projections 15a and 16a is tapered at theinput end so that, as shown in the regions I51) and 11671 (Fig. 4), theexternal diameter of each projection and the root diameter of the coresupon Which the projections are carried are progressively reduced at oneend of each roller. At the output end the rollers IS'and 1 5 terminateina solid cylindrical end portion and 166, equal in diameter to that ofthe maximum external diameter of the "projections. The portions 150 and16c tend to exert a braking and polishing action on'the debarkedtimberas it'p'asses through the machine in the direction of the arrow'Ain'Fig.3. j

It will bea'pp'reci'ated' that any timber introduced onto therotating-debarking rollers 15, 16 without any other co-opera-tingmembers'b'eiiig provided, would simply result in a rapid conveying ofthe timber through the machine without any stripping thereof takingplace. To prevent this a pressure element is? provided to force thetimber against the" debarking rollers 15, 16 and ensurev that the woodrotates at a speed slower than the debarking rollers,

so that they do in fact strip the'bark and bast from the timber. I V

In the embodiment illustrated, the pressure-exerting member isconstituted by a roller 23, of greater diameter than the debarking'rollers, rotatably mounted above rollers 15, 16 in bearings 2512,2413carried by aplatforrn 25 at one eiid of'anarm miz', thefother end ofwhich arm is pivposition are provided (see Fig.'5)., These meanscomprise a bolt 27, mounted rigidly on arm a by a system.

of lock nuts and depending through aslot 25b in platform 25.'Beneaththisplatform, bolt 27 carries-a sleeve 28 threadedly engagedtherewith, which sleeve has a lever 28a attached thereto and also has aflange on its upper surface adapted to bear against the underside ofplatform 25; Movement of lever 28a can thereby lock or unlock platform25 and its associated parts relative tothe arm 10a. By moving lever 28ato its unlocked position, the platform 25 and roller 23v can be adjustedabout point 26 within the limits-of slot 25b until the desiredorientation of roller 23 with respect torollers and'16 is obtained, andthen the pressure head can be locked in that position by lever 28a.Handle 25a is provided to facilitate adjustment, so that it is possibleto vary the speed of progression of timber passing through the machine.

Pressure roller 23 is naturally urged towards debarking rollers 15 and16 by gravity due to its own weight, and that of arrnltla and associatedparts. This is supplemented however by spring force provided byheavy-duty springs 29 arranged between arm 10a and lever 30 pivoted atone end at 30a to an upright of the main framework. The other end oflever 30 carries a hand grip so that the machine operator can engage thelever in any one of a number of notches provided in a plate 31 fastenedto another upright of the main framework, and by this means adjust thespring force that urges pressure roller 23 downwards.

The movement of roller 23 and arm 10a in an upward direction is effectedby an effort applied by the operator. A steel rope 32 attached to a lugon the arm 10a passes over pulleys mounted in'the top of the machine andis connected to a hand lever 33, whilst a further steel rope 34 mayconnect hand lever 33 to a foot pedal 35. In this waythe. lifting of thepressure roller 23 can be effected by a combined hand-and-foot action.An adjustable stop member 36 is provided to limit the amount of downwardmovement of the pressure roller 23 by control of the upward movement offoot pedal 35. Stop 36 can also .be used to retain pressure roller 23 ina retracted (upward) position, by fixing the foot lever in its lowermostposition, in the event that it is necessary for the operator tothaveaccess to rollers 15, 16 for the purpose of cleaning, renewing or thelike.

The pressure roller 23 is formed with rubber end portions 23a and atoothed central metal portion 23b. It is driven at a slower speed thanroller 15, 16 by an overhead shaft 37 carried on bearings in arm 10a andis provided with suitable couplings, such as universal couplings 62, toallow the adjustment of the pressure head previously described.Reduction gear 38 transmits the rotation of shaft 37 to sprocket 39,which drives sprocket 40 on shaft 41 of roller 23 through chain 42.Shaft 37 receives its drive through a pulley 43 mounted thereon, a belt44 and a pulley 45 carried by a primary countershaft 46. A dou- 'blepulley 47 also carried by countershaft 46 is connected by belt 48 topulley 49 on secondary countershaft 22 to drive the latter, and is alsoconnected by belt 50 to the driving pulley 51 of a prime mover 52 forthe machine. In this manner a common power unit such as a diesel orpetrol engine, serves to drive both debarking rollers and the pressureroller.

In operation, the pressure roller 23 is adjusted and fixed so that itsaxis of rotation is such that it will have 'a conveying or feedingaction on the timber when brought type of timber being treated. Due tothe'surface of roller 23 gripping the wood, they both rotate at the samespeed. The debarking rollers are rotating much faster and effect astripping of the bark and bast from the timber. The'amount of strippingcan be controlled by adjust ment of pressure by lever 30. The timberleaves the machine at C (Fig. 3). s 1

A limit stop maybe provided totprevent downward dis 7 placement of thearm 10a and associated parts so as to avoid the pressure roller cominginto contact with the de-.

barking rollers in the event of breakage of rope 32. This stop isconveniently constituted by a rod 53 pivotally a tube 54 pivotallymounted on the main framework 10. If rope 32 breaks, arm 10a will fall,but before roller 23 comes into contact with debarking rollers.15, 16rod 53 abuts against a solid portion 54a of'tube 54, so that furtherdownward movement is prevented. If 'desired, holes (not shown) boredthrough rod 53 and tube 54 may be used together with a co-operating pinto prevent movement of arm 10a and its associated parts duringtransportation.

An impeller 55 is arranged below the debarking rollers 15, 16, onsecondary countershaft 22 (Figs. 2 and 3) for the purpose of disposingof bark fragments which drop down during the debarking process, andwhich are shot out against a shield 56 arranged behind the rollers. The

impeller is arranged to deliver the bark fragments through a duct 57 sothat they may be readily collected at one end of the machine. Arrowsindicate the path of the stripped bark.

A lead-in or guide trough 58 hinged and locked around the debarkingrollers is provided to protect the operator.

from the moving parts and to prevent logsof unusual or irregular shapefrom breaking loose or becoming ejected. prematurely. The trough maybeat least partly composed of rubber, so that its shape is readilyadapted toirregular timber. may be provided and if this is a flexiblemember it will accommodate timber of awkward or unusual shape. Such asupport may be in the form of a chain 59 arranged between small uprightstanchions 60 on the main framework 10.

Preferably arm 10a is guided in its vertical movement by rollers 61mounted thereon and bearing against uprights of the main framework 10. 7

Suitable guards 63 are arranged over chain and other drives in normalmanner.

Conveniently a roof 64 is arranged over the machine,

and canvas side and end pieces 65 may be provided for" lowering intoposition during transportation.

As stated the machine is particularly suitable for small lengths ofround timber. It, is quite common for the latter to have a considerablenumber of knots and other irregularities near the surfaceand such hardpieces of wood would tend to override the stripping projections andsimply lift the timber slightly in the machine and push the pressureroller 23 upwards against the force exerted by its weight and thesprings. To overcome this, breakers, 15d, 16d are introduced at spacedintervals between the convolutions of each projection 15a, 16a; Thesebreakers 15d, 16d comprise narrow bars staggered with respect to oneanother (Fig. 4) and may have a strengthened and sharpened leading edge,so that any knots or the like which they encounter are cut or brokenfrom the timber.

The smallness and compactness of the machine makes it readilytransportable, and as stated although it is designed for debarking shortlengthsof timber such as from one widelyvarying top diameters.

As the pressure applied to the timber is readily variable Afurther'support for long lengths of timber' of wood removed on thepassage of the logs through the machine. Furthermore, it is possible todeal with batches of timber of mixed types, species and conditions, andsorting before debarking is not necessary.

With the machine illustrated, it is possible to debark about 150 cubicfeet of timber of an average of four to five inches diameter per hour. Asuitable speed for the debarking rollers 15, 16 is about 750 revolutionsper minute, in which case the pressure roller 23 may be driven at aspeed of about 30 revolutions per minute.

We claim:

1. A debarking machine for timber comprising rotating stripping meansformed by a pair of debarking rollers carrying helical projections foreffecting the debarking of timber, and a pressure-exerting memberconstituted by a roller mounted above said debarking rollers forrotation about an adjustable axis, said debarking rollers each beingdriven in the same direction as, but at a greater speed of rotationthan, that of said pressure-exerting roller and being adapted to conveytimber being stripped through the machine, and said pressure-exertingroller being arranged to hold said timber against said helicalprojections and control the speed at which said timber is conveyedthrough the machine.

2. A debarking machine for timber comprising rotating stripping meansformed by a pair of debarking rollers each having a tapered end portion,a central portion and a solid cylindrical end portion, and apressure-exerting member, said tapered and central portions of each ofsaid debarking rollers having helical projections, said debarkingrollers each being driven in the same direction and being adapted toconvey timber being stripped through the machine from said tapered endportions, and said pressure-exerting member being arranged to hold saidtimber against said debarking rollers and control the speed at whichsaid timber is fed through the machine.

3. A debarking machine for timber comprising rotating tripping meansformed by a pair of debarking rollers carrying helical projections forefiecting the debarking of timber, and a pressure-exerting member, saiddebarking rollers having breaker bars fitted at spaced intervals betweenconvolutions of said helical projections, being driven in the samedirection of rotation and being adapted to convey timber being strippedthrough the machine, and said pressure-exerting member being arranged tohold said timber against said helical projections and control the speedat which said timber is fed through the machine.

4. A debarking machine for timber comprising rotating stripping meansformed by a pair of debarking rollers, and a pressure-exerting memberconstituted by a roller mounted above said debarking rollers forrotation about an adjustable axis, said debarking rollers each beingdriven in the same direction at a greater speed of rotation than that ofsaid pressure-exerting roller and being adapted to convey timber beingstripped through the machine, and said pressure-exerting member havingrubber end portions and a toothed, central, metal portion whereby tohold said timber against said debarking rollers and control the speed atwhich said timber is fed through the machine.

5. A debarking machine for logs comprising a prime mover, apressure-exerting roller driven by said prime mover, and debarking meansconsisting of a pair of debarking rollers also driven by said primemover in the same direction as but at a much greater speed than saidpressure-exerting roller, each of said debarking rollers having ahelical projection and breaker bars arranged between the convolutions ofsaid projections parallel to the axes of said rollers, said debarkingrollers effecting a stripping of logs which are conveyed through themachine at a speed controlled by said pressure-exerting roller.

6. A debarking machine for logs comprising a prime mover, apressure-exerting roller driven by said prime mover, and debarking meansconsisting of a pair of debarking rollers also driven by said primemover in the same direction as but at a much greater speed than saidpressure-exerting roller, each of said debarking rollers having ahelical projection, each of said projections being of uniform diameterover a portion of its length and then tapering towards the infeed end,said debarking rollers effecting a stripping of logs which are conveyedthrough the machine at a speed controlled by said pressure-exertingroller.

7. A debarking machine for logs comprising a prime mover, apressure-exerting roller driven by said prime mover and debarking meansconsisting of a pair of debarking rollers also driven by said primemover in the same direction as but at a much greater speed than saidpressure-exerting roller, each of said debarking rollers having ahelical projection of similar pitch, said projections being of uniformdiameter over a portion of their length and then tapering towards theinfeed end, each debarking roller having a solid cylindrical portion atthe outfeed end of equal diameter to the projection, said projectionsefiecting a stripping of the logs which are conveyed through the machineat a speed controlled by the pressure-exerting roller.

8. A debarking machine for logs comprising rotating stripping meansformed by a pair of debarking rollers member, said tapered and centralportions of each of said mounted above said debarking rollers forrotation about an adjustable axis, said pressure-exerting roller havingrubber end portions and a toothed central portion, said debarkingrollers being driven in the same direction at a greater speed ofrotation than that of said pressure-exerting roller and being adapted toconvey the logs through the machine, said pressure-exerting roller beingarranged to hold said logs against said debarking rollers and controlthe speed at which said logs are fed through the machine.

References (Iited in the file of this patent UNITED STATES PATENTS1,300,748 Lombard Apr. 15, 1919 2,015,936 Hokonson Oct. 1, 19352,390,459 Power Dec. 4, 1945 2,669,266 Bouchard Feb. 16, 1954

